The transabdominal approach allows evaluation of various pelvic and intra-abdominal structures, including the hepatorenal space (Morison pouch) and gallbladder [12]. The transabdominal view has two planes: sagittal and axial (Fig. 7.3). Often the sagittal view is described as longitudinal. The axial plane may be described as transverse. To begin, hold the probe in the right hand with the thumb touching the probe’s orientation marker (often a ridge). The marker should correspond to a dot on the upper left portion of the screen. Images at the top of the screen are closer to the probe. Images at the bottom of the screen are farther away from the probe.

During a transvaginal ultrasound, the endocavitary probe (EC) operates at depths between 5 and 10 cm. The anatomy is visualized in two planes: the longitudinal (sagittal) (Fig. 7.4) and the coronal (transverse or axial) (Fig. 7.5). Before starting the examination, ask the patient to empty their bladder to make the exam more comfortable for the patient and to improve visualization. The operator places conductance gel on the probe tip and covers the transducer with a sheath or condom. The sonographer then places lubricant on the outside of the cover. After informing the patient, the EC probe is inserted and the exam begins with the marker at the 12 o’clock position.

By convention, the longitudinal view is the first plane obtained when performing TVS. When the probe marker points toward the ceiling, the sagittal plane is displayed on the screen with clear visualization of the long axis of the uterine body and endometrial stripe. The cervix is on the screen’s right side, and the bladder is on the screen’s upper left portion (Fig. 7.6). Difficulty obtaining this standard view can signify anatomical variation or erroneous machine settings.

To obtain a coronal view of the uterus, rotate the EC probe counterclockwise 90° moving the marker from the 12 o’clock to the 9 o’clock position (Fig. 7.7). The image plane is now perpendicular to the uterine body and divides the patient into cephalic and caudal regions.

The screen’s left and right sides should represent the patient’s right and left, respectively. The transvaginal probe is moved vertically or horizontally or may also be rotated. These maneuvers can be disorienting but gather essential information for diagnosis. The sonographer maintains orientation by limiting the probe’s rotation to the 90° between 9 and 12 o’clock.

To systematize the description and performance of bedside TVS, we divide the pelvis into nine sectors to be evaluated in both the longitudinal and coronal planes (Fig. 7.8).

The cervix is the lower portion of the uterus that communicates with the vagina through the endocervical canal. Like the uterus, the cervix is a vascular, hormonally responsive tissue with glandular components. These endocervical glands can become obstructed (Nabothian Cysts) (Fig. 7.9), especially during ovulation. The cervical length (CL) should be measured transvaginally in the sagittal plane using a straight line to connect the internal and external os, the [13]. The CL reliably predicts the likelihood of preterm birth [14, 15]. It is usually greater than 30 mm. When it measures less than 25 mm prior to 24 weeks gestation, the cervix is considered shortened [14, 16, 17].

The average nongravid uterus measures 7 cm long and 3–4 cm in width and height [18]. The uterine volume increases after each pregnancy. Roughly the size and shape of a pear, the nulliparous uterus is composed of three layers: the covering serosa , the muscular hypoechoic myometrium , and the dynamic hyperechoic endometrium that lines the intrauterine cavity [19].

The relationship between the uterine body and cervix determines uterine position. To describe this relationship, the sonographer relates the long axis of the uterus to the vaginal canal (version) and cervix (flexion).

The fallopian tubes cannot be visualized in the absence of pathology or iatrogenesis. Near the patient’s midline, the uterus surrounds the interstitial portion of the salpinx. The extrauterine isthmus widens into the infundibulum and fimbria, which opens directly into the peritoneum. A visible, fluid-filled hydrosalpinx suggests previous tubal surgery or pelvic inflammatory disease (PID). A hydrosalpinx may appear cystic with incomplete septations and endosalpingeal folds that look like “beads on a string.” The dilated fallopian tube should be differentiated from the adjacent ovary to ensure a correct diagnosis [20].

Like the uterus, the ovary is a hormonally responsive organ that changes appearance with the menstrual cycle. The ovaries are measured in three perpendicular orthogonal planes. The transvaginal longitudinal plane best measures the length and height (anterior–posterior diameter); the transvaginal coronal view best measures the width. Premenopausal, nondominant ovaries measure approximately 2 cm × 2 cm × 2 cm [21]. A normal, nondominant ovarian volume measures less than 10 cc.

Ovarian volume decreases with age and oral contraceptive use [21]. Initially, each ovary contains several follicles that measure less than 1 cm in diameter. After 7 days, a single ovarian follicle emerges and will grow to a diameter slightly greater than 2 cm. This dominant follicle will then rupture and become the vascular corpus luteum, which on sonography has a crenulated appearance and thickened wall [22].

On transvaginal ultrasound, 2 % of pregnant women and 10 % of all women will have a functional ovarian cyst or cysts [23, 24]. Follicles generally have a diameter less than 2–2.5 cm, and a cyst’s diameter usually exceeds 2.5 cm. For simple cysts in premenopausal women, repeat ultrasound at 6-week intervals so the images will correspond with a new cycle at a different phase than the previous examination. If a cyst is unilocular and has a diameter less than 10 cm, the malignant potential is less than 0.1 % [20, 25].

The corpus luteum forms in the potential space left by a ruptured, dominant follicle. Corpus luteum cysts are the most common ovarian masses during early pregnancy. These cysts can hemorrhage, torse, or rupture. Under these circumstances, patients present with acute abdominal pain. In pregnancy, corpus luteum cysts (Fig. 7.16) may persist for 16 weeks and exceed 10 cm in diameter [26–28].

With a rich vascular supply, the cystic morphology of the hemorrhagic corpus luteum has a varied appearance that is related to the formation and absorption of blood clots. On ultrasound, hemorrhage can have a reticular, cobweb appearance within a complex cyst. In general, cystic hemorrhage should resolve within 2 months [20].

For premenopausal women:

A hemorrhagic cyst in a postmenopausal woman is considered malignant until proven otherwise.

Pelvic pain can be classified as either acute or chronic and is related to menses and pregnancy. The investigation of pelvic pain drives almost half of gynecological diagnostic laparoscopies [29]. In general, non-cyclic chronic pelvic pain must persist for at least 3 months irrespective of menses. Cyclic chronic pelvic pain changes with relation to the menstrual cycle and persists for at least 6 months [26]. Common causes of both cyclic and non-cyclic chronic pelvic pain include endometriosis, adenomyosis, postoperative adhesions, and fibroids. For this chapter, our focus is on acute pelvic pain related to the adnexa and uterus in the nonpregnant patient [30].

Adnexal torsion is a sudden disruption of adnexal arterial blood flow. Patients with ovarian torsion experience acute abdominal pain. Risk factors include preexisting adnexal enlargement, often secondary to an occult teratoma or ovarian cyst. Use the following facts to aid rapid diagnosis and intervention: [26, 29, 31].

PID includes endometritis, salpingitis, tubo-ovarian abscesses, and pelvic peritonitis. The Centers for Disease Control (CDC) , specify in their diagnostic criteria for PID that the patient must have uterine, adnexal, or cervical motion tenderness [30, 32]. In the USA, PID is diagnosed over one million times annually. The incidence of chlamydia has quadrupled over the last 25 years, with particularly high rates in urban environments. In some neighborhoods, more than 25 % of young women test positive for chlamydia [33].

Without treatment, many women with PID will partially resolve the initial painful symptoms but will become infertile secondary to chronic inflammation. For diagnosing PID, pelvic ultrasound has a high sensitivity and specificity and may simultaneously exclude other obstetrical and gynecological causes. A dilated, fluid-filled hydrosalpinx is present in most cases of PID . Cine-looping can help differentiate a folded, dilated tube from a septated cyst. Color Doppler can distinguish an iliac vein or anomalous varix from a dilated fallopian tube.

Salpingitis is inflammation of the fallopian tube that can progress to an abscess (Fig. 7.17). Tubal inflammation and its sequelae fall within the broader categories of acute or chronic PID. Sonography has improved the clinician’s ability to accurately diagnose pelvic infectious disease: [3, 26, 34]